feat: implement provide/inject API to transfer data from the main thread

[sheremet-va]

Description

Closes #4025

This PR adds project.provide API that allows transfering data from the main thread like global setup to tests. This API cannot be used to transfer data back to the main thread - users need to implement that themselves. If they want to keep communication inside Vitest, it's recommended to use task.meta to transfer data back to the main thread alongside tests.

To get the data, you need to write import('vitest').inject(key) inside the test:

// globalSetup.ts
declare module 'vitest' {
  export interface ProvidedContext {
    dbUrl: string
  }
}

export default async ({ provide }) => {
  const db = new DB()
  const url = db.getUrl()
  provide('dbUrl', url) // has typechecking
}

// db.test.ts
import { inject } from 'vitest'
const dbUrl = inject('dbUrl') // typed as a string
const connection = new Connection(dbUrl)

provide is scoped to the project since global setup is also scoped the same way. provide API uses strings as keys because symbols are not transferable between threads/websocket/forks. It is possible to override values by using the same key (internally it's just an object with string keys)

You can only transfer serializable data! The rules for serialization are the same used for task.meta: https://vitest.dev/advanced/metadata.html

Please don't delete this checklist! Before submitting the PR, please make sure you do the following:

• It's really useful if your PR references an issue where it is discussed ahead of time. If the feature is substantial or introduces breaking changes without a discussion, PR might be closed.
• Ideally, include a test that fails without this PR but passes with it.
• Please, don't make changes to pnpm-lock.yaml unless you introduce a new test example.

Tests

• Run the tests with pnpm test:ci.

Documentation

• If you introduce new functionality, document it. You can run documentation with pnpm run docs command.

Changesets

• Changes in changelog are generated from PR name. Please, make sure that it explains your changes in an understandable manner. Please, prefix changeset messages with feat:, fix:, perf:, docs:, or chore:.

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